Message-ID: <000101bf64a9$3ea4c6a0$881c01d5@dave>
From: "Dave Sergeant" <sergeantd@compuserve.com>
To: "rsgb_lf_group" <rsgb_lf_group@blacksheep.org>
Subject: LF: RX Input filters
Date: Fri, 21 Jan 2000 19:32:14 -0000
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>From Dave G3YMC

I also use a sharply tuned front end to my receiver, having a fixed tuned
circuit at the input of my receive converter and a second one at the output
of the FET preamp.  Bandwidth is around a couple of kHz, which is adequate.
DCF39 is already down on the filter slope and is probably why I give lower
reports on it than some.  I suffer no signs of receiver crossmod.  The
circuit can be found on my web site.

Sound bias oscillator transformers from scrap VCRs make ideal transformers
for this purpose - you will fiind one in the bias oscillator of virtually
every video made, audio tape recorder ones may also be suitable.  The
secondary high output winding of these transformers usually has an
inductance of 1-2mH, and can be easily resonated on 136.

73s Dave G3YMC
dsergeant@iee.org
http://ourworld.compuserve.com/homepages/sergeantd